Heat-cutting method for overlapping metal plates



United States Patent 3,468,726 HEAT-CUTTING METHOD FOR OVERLAPPING METAL PLATES Kozo Sato, 89 Yamamoto-cho, Minami 3-chome, Yao, Osaka Prefecture, Japan No Drawing. Filed Mar. 14, 1967, Ser. No. 622,892 Claims priority, applifiation Japan, Dec. 2, 1966,

53 Int. Cl. B23]: 7/58,- czar 17/00 US. Cl. 148-9 3 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method of heat-cutting two overlapping metal plates at a time by applying a paste consisting of specific substances to the part to be cut prior to the gas or electric heat-cutting operation.

In case metal plates are heat-cut by taking advantage of gas or electricity, it is desirable from the viewpoint of operational efficiency to put two plates one over the other and cut them at a time. There are, however, various difficulties in this method. For instance, in case of heatcutting two metal plates at a time by means of gas, there is a defect of a great deal of heat being lost as a result of dispersion of heat from the gaps left between the two metal plates. This is the bottleneck in the operation of simultaneous heat-cutting of two metal plates with gas.

Quite recently, however, it has been discovered that the heat dispersion loss at the part to be cut can be minimized and heat-cutting operation can be executed effectively when the metal plates are pressed closely together by means of applying powerful pressure from outside the overlapping metal plates.

The above-mentioned method, however, requires a huge pressing equipment to press the metal plates closely together, as a result of which there arise financial difliculties, such as increased costs of equipment and greater space workshop.

The electric heat-cutting method for overlapping metal plates, which has long been practised, is also attended with no less difficulty. The greatest one in this case lies in the fact that slags produced during the heat-cutting operation stick fast along the cut edge, making the metal plates inseparable after the heat-cutting operation is complete. This involves the trouble of having to scrape the slags off the overlapping cut edge after the operation by means of a chisel, resulting in a great loss from increased labor costs. Adoption of this method, therefore, does not mean any improvement in the operational performance after all, because the increased efliciency is counterbalanced by the increased labor costs.

A careful examination on the above-mentioned traditional heat-cutting methods leads to the conclusion that physical factors alone are taken into account in case of such methods, and this is the reason why the gas or electric heat-cutting method for overlapping metal plates has come to a technical deadlock. It is of vital importance, therefore, to overcome this deadlock by removing the fundamental cause thereof. From this viewpoint the author of this invention has included chemical factors in his research and succeeded in completing a new simultaneous heatcutting method for overlapping metal plates.

This invention is characterized by the application of paste to the part to be cut which is a compound of a substance which has enough stability at high temperatures and forms a fused film on contact with the cutting heat and another substance which generates such a gas when pyrolyzed as will react upon the fused metal and turns it 1nto non-adhesive slag.

The paste is first applied to the part to be cut of the two metal plates, and then such metal plates are pressed 10 together with the paste sandwiched in between, allowing no gap to remain between the overlapping parts. Consequently, satisfactory contact between the two metal plates can be obtained with less pressure than in the case of the traditional method which requires huge pressure.

Moreover, the paste is mostly composed of a substance which has enough stability at high temperatures and forms a close-fitting in a fused state on contact with the cutting heat, so that close contact can be easily maintained, preventing heat dispersion loss from the overlapping parts of the metal plates even under intensely heated conditions.

As a result, even in case of the heat-cutting by the use of gas, there scarcely arises any thermal loss owing to dispersion of heat from the gaps left between the two metal plates, and the gas heat-cutting can be executed with extremely great effect and efficiency. Moreover, this method has a still greater advantage, i.e. it effectively prevents the fused slags which are produced during the heat-cutting operation from encrusting over the cut edge of the overlapping metal plates.

0 The substance contained in the paste which turns fused metal into non-adhesive metal waste, such as iron slag, functions as follows: it is pyrolyzed and produces gas when brought into contact with the cutting heat and this gas reacts upon the fused metal layer and turns it into nonadhesive slags, such as iron sulfide and iron chloride.

Therefore, the slags, though they appear to be clinging fast to the cut edge of the overlapping metal plates, come ofi easily after the heat-cutting operation is complete.

Here is the explanations of two embodiments of this invention. The following lists show instances of the paste used in this invention.

EMBODIMENT I.-Water soluble type EMBODIMENT lI.-Non-water soluble type Chemicals Mixing ratio (percent in weight) Aluminium hydroxide powder 7 Glass powder 7 Parafiin chloride "a 0.5 Sulfur powder 0.5 Carbon 5 Pasted epoxy resin and its hardener or other natural or synthetic resins 60 Plasticizer 20 The paste is prepared by carefully mixing the abovementioned chemicals each at the said ratio. The paste is applied to each opposite surface of the two metal plates before they are put together, and this helps bring the metal plates into close contact with each other.

The surface tension of the said paste being held below at 20 C. 40 dyne/cm., the paste partly penetrates into 3 and settles inside the inner surface composition of the metal plates placed one over the other, thus producing very close contact between the two plates.

The two plates, laid one over the other with the paste sandwiched in between, are so closely bound together in an integrated Whole that there scarcely arises anyheat dispersion loss from between the two overlapping plates, thus making it possible to heat-cut the two plates with extremely high thermal efficiency. Moreover, fused slags seldom sticking to the cut edge of the metal plates, the two overlapping sheets can be severed with case after the heat-cutting operation is complete.

What I claimv is:

1. A'method of heat-cutting stacks of metal plates comprising applying between' the plates apaste composed of a compound consisting of a substance having enough stability to form a film at cutting temperatures and a substance which generates gas and prevents fused metal from adhering to the plates, and heat-cutting the stacked metal plates.

2. The method as set forth in claim 1, in which the paste applied to the plates to be cut is composed of aluminum hydroxide, mica, graphite, glass, either paraffin chloride or diphenyl chloride, sulfur, silicone, sugar ester, surfaceactive agent, and polyvinyl alcohol or carboxyl methylcellulose.

3. The method as set forth in claim 1, in which the paste applied to the plates to be cut of the overlapping metal plates is composed of aluminum hydroxide, glass, paraffin chloride, sulfur, carbon, a plasticizer, and a resin taken from the group consisting of epoxy resin and hardener therefor, natural, resin, or synthetic resin.

References Cited UNITED STATES PATENTS 2,538,876 1/1951 Meincke l48---9 3,338,757 8/1967 Dodge at al. 143-4 L. DEWAYNE RUTLEDGE, PrimaryExaminer W. W. STALLARD, Assistant Examiner 

